1. Field of the Invention
The present invention relates to a device for packaging a material web roll with a packaging sheet. The device includes a packaging sheet dispenser that is movable parallel to an axial direction of the material web roll and that dispenses a packaging sheet to at least one part of the axial length of the material web roll at an angle to the axial direction of the sheet or web roll. The angle being acute with respect to a lateral direction of the material web roll. The device also includes carrier rolls positioned such that the material web roll rests on the carrier rolls.
The present invention also relates to a method for wrapping a material web roll with a packaging sheet such that the packaging sheet is wrapped around the material web roll along a helical line.
2. Discussion of Background Information
A device and a method similar in general to that discussed above are known from, e.g., GB 1 429 445, in which a plastic sheet is wrapped in a helical line around a material web roll. At the axial ends of the material web roll, an angle between the packaging sheet dispenser and the material web roll is aligned to 90.degree. and the sheet is further wound around the material web roll to create end packaging. Once provided with circumferential packaging, the material web roll is guided through a heating furnace to shrink-wrap the plastic sheet onto the material web roll.
Packaging a material web roll within a packaging sheet guided along a helical line around a longitudinal axis of the material web roll has the advantage that a plurality of material web rolls having varying widths can be wrapped with a single width of packaging sheet. Thus, this arrangement simplifies the supply and the handling because the packaging sheet can be narrower than the material web roll. Further, its weight is correspondingly lighter.
However, using plastic wrap as the packaging sheet may present certain disadvantages with respect to environmental problems. However, the use of packing paper as the packaging sheet causes other problems. The body packaging wrapped around the material web roll along the helical line must be separated from each end packaging on the axial ends of the material web roll by cutting through the packaging sheet running in the circumferential direction. Then the packaging sheet must be realigned to the material web roll and fastened thereto, e.g., as discussed in DE 195 35 746 A1.
It has been observed that the material web roll also has a tendency for axial migration during production of the body packaging. That is, during the helical wrapping of the material web roll with the packaging sheet, the material web roll may migrate or move, e.g., one or more centimeters, in its axial direction. This migration may be caused by the fact that, during production of the body packaging, the material web roll exhibits a larger diameter on one end of the roll than on the other. With each rotation, the roll thus migrates slightly in a direction of the larger diameter. Because several rotations of the material web roll occur during the packaging procedure, a correspondingly great migration results. Thus, when the packaging sheet dispenser is placed in a new position, under certain circumstances, the end packaging may not be attached at the desired location, but, rather, unintentionally axially displaced along the length of the material web roll.